I need to remove the EFI partition on my USB because when trying to copy files from my PS4, the PS4 chooses this partition and ultimately runs out of space, instead of using the much larger space.
The EFI is about 200MB big and the USB storage is 16GB, apparently the only way to get the PS4 to write onto the large partition is to get rid of the EFI Partition.
Apple automatically and transparently creates an EFI partition on any GPT formatted disk (which is the default format). To get rid of it, you must reformat the flash drive with the MBR partition scheme.
In Disk Utility, choose the flash drive itself (not the volume under it) and choose Erase from the toolbar. In the window that comes up, make sure you have MS-DOS (FAT) selected as the format type (not shown in the screenshot below) and Master Boot Record selected as the scheme type.
NOTE: Make sure you select MS-DOS (FAT) as the format type. I grabbed and posted the screenshot before I realized I had the wrong format showing.